Medical imaging systems are used to obtain images of a patient's body. For example, medical imaging systems based on ultrasound technology transmit high frequency sound waves into a patient's body and then receive and process returning echoes to obtain two or three dimensional images, for example, time-varying images. Medical imaging systems in general and ultrasound imaging systems in particular are known in the art.
Various types, or modalities, of imaging are known in the art. For example, there are algorithms for producing B-mode images (brightness), C-mode images (color), D-mode images (Doppler), M-mode images (motion), combination modes (e.g., B+C or B+D or B+C+D), or the like. During use, an imaging system may be switched from one mode to another at the whim of the operator (e.g., a physician or a technician).
FIG. 1 schematically illustrates a conventional ultrasound imaging system 100. The conventional system 100 includes: a front-end portion 110a that includes a scanner and a processor, and a back-end portion 112a that includes a processor. The front-end portion 110a includes, or works with, an ultrasound probe 114a. The back-end portion 112a includes, or works with, a display 116b. The conventional system 100 uses, for example, a serial bus 120 (for example, USB (Universal Serial Bus) 2.0 or IEEE1394 FireWire™) for ultrasound image data transfer between the front-end portion 110a and the back-end portion 112a. The serial bus 120 utilizes an Isochronous channel 122 for transferring image packets and an Asynchronous channel 124 for transferring Command and Control parameters. Command and Control parameters include, for example, instructions to switch into particular modes, as well as mode-specific parameters (e.g., frame size, number of zones, time sequence information, and the like) including parameters that define how to interpret the image packets of the Asynchronous channel. The Isochronous channel 122 supports a real-time, high-throughput image-data transfer, in which a data packet can be dropped if the throughput of the channel becomes problematic. There is no guarantee that any particular image packet will be transferred, but the image frames that are transferred will always be in real time. In contrast, the Asynchronous channel 124 has a lower priority in sharing the channel bandwidth and supports packet transfer without any guarantee of real-time delivery, for low-throughput command and parameter communication.
FIG. 2 schematically illustrates another conventional ultrasound imaging system 150. The conventional system 150 includes: a front-end portion 110b that includes a scanner and a processor, and a back-end portion 112b that includes a processor. The front-end portion 110b includes, or works with, an ultrasound probe 114b. The back-end portion 112b includes, or works with, a display 116b. The conventional system 150 uses a PCI bus 160 to transfer ultrasound image data and control parameters between the front-end portion 110b and the back-end portion 112b. The PCI bus is a parallel bus inside the PC motherboard that supports, e.g., a 132 Mb/s throughput rate with a critical timing requirement.